Jack base



FIG. 1 is a perspective view of the jack base of the present invention;

FIG. 2 is a side elevation of the jack base. The opposite side elevation is identical to FIG. 2;

FIG. 3 is a front elevation of the jack base. The rear elevation is identical FIG. 3;

FIG. 4 is a top plan view of the jack base; and,

FIG. 5 is a bottom plan view of the jack base. 

The ornamental design for a jack base, as shown and described. 